I heard from a reputable engine builder that sometimes if your engine bearings are a bit too small you can use paper shims under the caps. now paper usually measures .005" but has anybody tried this and knows how much the paper will actually compress when the caps are torqued. Thanks.

 

Hmmn. since you can get metal shims in .0001 and above, I'd wonder why mess with a compressable shim.

That said, my feeling is your "reputabe engine builder" hasn't done much building since insert bearings have become the norm.

Many, many years ago, when bearings were poured (babbit) and they became worn, it was common to file the caps...also common to shim them if too tight...issue is regardless of whether you're shimming or filing the caps, your caps are no longer round, but either "oval'ed" by the shim, or "eye'd" by filing.

 

If paper will compress, it will also spring back, so that when the engine is shut off all oil will be squeezed out of the bearings and you'll be "stroking dry" - mot my preferred method, for sure.

If the bearings are that loose, it's time to polish the crank and install undersize shells.

APO? Does that mean all you get is air mail?